class Dog():
    """一次模拟小狗的简单尝试"""

    def __init__(self, name, age):
        """初始化属性name和age"""
        self.name = name
        self.age = age

    def sit(self):
        """模拟小狗被命令时蹲下"""
        print(self.name.title() + " is now sitting.")

    def roll_over(self):
        """模拟小狗被命令时蹲下"""
        print(self.name.title() + " rolled over!")

# 创建一个实例, 传入参数name age
my_dog = Dog('white', 6)

# 打印name
print(my_dog.name.title())

# 打印age
print(str(my_dog.age))

# 调用方法 sit() roll_over()
my_dog.sit()
my_dog.roll_over()

your_dog = Dog('lucy', 3)

print("My dog's name is " + my_dog.name.title() + ".")
print("My dog is " + str(my_dog.age) + " years old!")
